Unplanned maintenance events can delay and possibly result in the cancellation of aircraft takeoff, which may increase operating cost and complexity, as well as negatively impact on-time delivery and overall customer satisfaction. An unplanned maintenance event can occur when an aircraft engine fails to start or responds sluggishly during Main Engine Start (MES). In this event, maintenance personnel may be dispatched to the aircraft to quickly determine if proper engine operation can be restored by replacing a Line Replaceable Unit (LRU) involved in the MES procedure. In the case of an air-started engine, the maintenance personnel may inspect any LRUs supporting MES, such as a starter air valve and an air turbine starter, for signs of oil leakage or other visual evidence of a fault. If the maintenance personnel determine that a particular LRU is likely at fault, the technician may perform an infield replacement of the LRU and MES may be reattempted.
To reduce the occurrence of unplanned maintenance events, aircraft engine are commonly subject to routine inspection at predetermined operating hour intervals. Routine inspection may entail an evaluation of the current condition or “health” of the LRUs installed on the engine. In this manner, an LRU can be replaced preemptively if the health of the LRU is questionable or if its serviceable lifespan is soon to expire. While this is advantageous, routine inspection practices remain limited in several respects. For example, by conventional practice, LRU health is typically inferred from data stored in a memory module associated with the engine controller. Consequently, it may be necessary to power-up the aircraft engine to access the data stored on the memory module and thereby inferentially determine LRU health. Not only does this add undesired time, cost, and complexity to the inspection process, but each engine start-up contributes to engine component wear. Furthermore, engine start often results in the generation of a number of unrelated messages, which can introduce confusion and further complicate the otherwise basic task of evaluating LRU health. Finally, the limited information stored the engine controller memory module often provides an incomplete picture of overall LRU health.